Side bags

I've noticed once and awhile when climbing aboard my 1995 r1100rsl I sometimes scuff the topside of the side bag with my boot but when I try to clean it the scuff never cleans up. Has anyone ever experienced this on their bike? Best way to clean it?

Approach bike on right side(opposite of kickstand) and lift heel to step over seat. The key is to step straight over the seat and not "swing" the leg. Fully loaded ADV bike guys use this technique since there is no way to swing a leg over the top box or tent/sleeping roll. Keeps any scuffs on the leather under your butt, instead of on the finish.